BIOCHEMICAL GENETICS AND RECOGNITION OF A WESTERN STOCK OF THE COMMONGEMFISH, REXEA-SOLANDRI (SCOMBROIDEA, GEMPYLIDAE), IN AUSTRALIA

Protein electrophoresis and analysis of restriction fragment polymorph ism in mitochondrial DNA (mtDNA) provided information on population/st ock structure of Rexea solandri. Two distinct Australian stocks are ev ident. with one (AAT-2) of 36 enzymatic loci and all 11 mtDNA digestio n profiles showing highly significant differences between eastern and southern/western Australian specimens. The split is at the western end of Bass Strait, with limited mixing off western Tasmania No external characters were found that would allow determination of the provenance of an individual fish. Stock distinction between eastern Australian a nd New Zealand fish is less clear; some differences, usually statistic ally non-significant, in genetic frequencies were found and some rare allozymic or restriction fragment variants were found in one or other but not both regions. Estimates of gene flow suggest that only tens of individuals per generation migrate between the regions. In an experim ent on tissue deterioration, after six days of exposure out of doors, significant amounts of intact mtDNA were present in all tissues, and a ll fragments of the HINF 1 phenotype were clearly scorable. Of 19 enzy mes tested, only three showed reduced activity on Day 6. Gonad and mus cle tissues were more resistant to degradation than was liver tissue.